There are two primary objectives of this research: 1) to use the technique of substrate stimulation of renal organic anion transport to gain further insight into the biophysics and biochemistry of this transport system in the kidney; 2) to further evaluate the effect of therapeutic agents on renal function in the newborn kidney and attempt to gain insight into the factors regulating renal function in the newborn. Two specific projects will be conducted in the coming year. In one we will continue our studies utilizing substrate utilizing substrate stimulation to investigate the interactions between lipid metabolism and the organic anion transport system. Secondly, we will extend and complete a series of studies relating to the role of the prostaglandins and the renin-angiotensin system in control of renal blood flow and electrolyte and water exretion by the newborn kidney.